大型射流流化床的流型转变与射流深度

FLOW REGIME TRANSITION AND PENETRATION DEPTH OF LARGE JETTING FLUIDIZED BED

在高 8m、直径 0 .5m的大型射流流化床中 ,通过摄像分析法 ,研究了射流、喷流两种流型的转变 .结果表明在低静床高、大射流气速下易出现喷流 ;喷流出现时 ,功率谱主频射流气速曲线上出现一转折点 .转折点射流气速与摄像法得出的流型转变射流气速相同 .提出了射流、喷流流型转变关系式 .同时发现射流深度随射流气速变大而增大 ,结合二维射流床射流深度的研究结果 。

In a 0.5 meter diameter semicircular jetting fluidized bed with 42 mm diameter semicircular nozzle, the transition of flow regime and the penetration depth were investigated. The penetration depth was recorded by a National M-7 video camera and analyzed frame to frame on a Panasonic HD-100 player. There were two flow patterns of jet and spout in a large jetting fluidized bed with increasing jet gas velocity. Spout appeared when jet gas velocity was high and static bed height was relatively low. The results from processing the signals of pressure fluctuation by multistage power spectrum analysis showed that the major frequency of pressure fluctuation increased with jetting gas velocity. On the basis of the experimental data, an equation describing flow regime transition was presented. Meanwhile, experimental data showed that penetration depth increased with the increase of jetting gas velocity. A correlation to penetration depth was also proposed.